31P magnetic resonance spectroscopy detects a functional abnormality in liver metabolism after acetaminophen poisoning.

Eighteen patients with acetaminophen poisoning were studied with 31P magnetic resonance spectroscopy to measure phosphorus-containing metabolites in their livers. The concentrations of all magnetic resonance-detectable metabolites fell in parallel with a decrease in the synthetic ability of the liver, indicated by the prothrombin time ratio (international normalized ratio). In particular, ATP fell to about 20% of its normal concentration in severely affected patients, as did the phosphodiester signal, which is thought to arise mainly from the endoplasmic reticulum in the liver. The correlation between ATP levels and international normalized ratio suggests that the international normalized ratio is a more accurate measure of the number of viable hepatocytes than are other biochemical tests.